Hydrolysis monitoring of Quinoa, Soy and Rice Proteins by using spectroscopy FT-IR technique

Abstract

The proteins that are subjected to hydrolysis processes increase their bioactive and functional properties, for this reason, in this work the protein hydrolysis was monitored by means of spectroscopy, to determine the structural changes that proteins undergo during hydrolysis. Enzymatic hydrolysis with endo / exoproteases was carried out on the three protein isolates, the enzymes used were Alcalase 2.4L and Flavorzyme® from the Sigma laboratory. The enzyme / substrate ratio was 5%; degrees of hydrolysis between 46% and 38.4% were obtained for Quinoa protein isolate and Rice protein isolate, respectively. Both follow-up of Quinoa protein isolate and Soy protein isolate enzymatic hydrolysis was 60 minutes with Alcalasa®2.5L and 120 minutes with Flavorzima®, with respect to Rice protein isolate, the established hydrolysis times were 60 minutes with Alcalase 2.4L and 20 minutes with Flavorzima®; Times longer than these, no significant differences were observed in the degree of hydrolysis. By way of comparison, the protein isolates and their hydrolysates were studied in the mid-infrared range (4000 cm^-1 to 600 cm^-1) to obtain information on the structure of the protein, for this, a technique was used deconvolution of the spectrum by means of the Fourier transform function. These spectra showed significant differences in the secondary structure of the protein, regarding the analysis of the areas, which were determined using a Gaussian function; the most favorable changes were mainly in the formation of b-sheet and b-turns structures.